16. Optics (Electromagnetics)
This problem asks the application of the Fermat’s principle of ray optics to another optics laws.
This principle shows the path of the light, so it can also be used to explain reflection and refraction of the light. So we can derive the Snell's law and the law of reflection from the Fermat's principle. Rayleigh’s criterion for resolution, however, cannot be explained by this principle. It can be derived from the diffraction.